Eucalyptus dilemma: Is the tree worth growing commercially?

Sunday May 31 2009


THE CONTROVERSY SURRO-unding the eucalyptus and its penchant for consuming far too much water leading to environmental depletion has led to confusion among commercial growers. Environmentalists, supported by government officials through the Ministry of Environment, are persuading Kenyans to uproot all trees of this genus grown near riverbeds and water catchment areas, without explaining where, and how best they should be grown.

At the same time, some forestry scientists and researchers claim that the stricture has no legal and scientific backing. But if Kenya followed the example of Punjab province of Pakistan, which has ordered all eucalyptus trees uprooted without replacement, then it means it will need to import most of the products best made from eucalyptus.

TO SUSTAIN THIS GROWING INDUStry without hurting the environment, the country should borrow a leaf from countries that have succeeded in eucalyptus farming as a heavy commercial venture. Critics say that growing eucalyptus disrupts hydrological balance in the soils, depletes soil nutrients, and inhibits the growth of other plants nearby.

Though no scientific studies have been done to ascertain that by the time of harvest, eucalyptus trees consume more water than indigenous trees, riverbeds and water catchment areas have evidently dried up more in areas where eucalyptus trees are grown than in areas with indigenous forests.

For example, it is reported that when South Africa’s natural forests and grasslands were converted into eucalyptus plantations, the flow of streams reduced in many parts of the country. This presents clear evidence that the trees have an enhanced capacity to exploit underground water.

Similar evidence has been gathered in nearly all countries where eucalyptus trees have been domesticated, Kenya included. However, this notwithstanding, it is not easy for one to understand how a genus with outstanding evolutionary adaptation to infertile soils and a dry climate in Australia will use excessive water when grown in other countries.

Explanations by critics put all blame on the tree’s rooting architecture and its deep penetration into the soils. However, a comparative study done a few years ago in São Paulo, Brazil (the world leading producer of eucalyptus products) indicated that a six-year-old Eucalyptus saligna plantation lost 12.2 per cent of rainfall water through canopy interception by the time of harvest.

Two 13-year-old pine plantations lost 12 per cent of rainfall water by the time of harvest. But savannah-like vegetation showed a loss of 27 per cent. The South African government teamed up with the private sector to conduct ecological zoning aimed at determining particular areas fit for growing eucalyptus without affecting water flow.

The same happens in Brazil, Chile and many other countries that have embraced commercial growing of eucalyptus. Kenya can do the same. Already, one ecological zoning done in Kenya through a study headed by Prof Senelwa Kingiri of Moi University has identified a potential of 4.2 million acres of land as ecologically suitable for growing eucalyptus.

Most of the eucalyptus trees grown in South Africa are technologically engineered to make them environment-friendly, to enhance faster growth, and to make them grow straight and uniform, making them ideal for products needed in the market.

AS A RESULT, THE COUNTRY HAS BEcome Africa’s leading producer of hardwood products made out of eucalyptus woodlots grown on an estimated 2.4 million acres countrywide. This figure compares poorly to Kenya’s 148,000 acres. Eucalyptus products from South Africa are therefore exported to different countries including Australia (the motherland of eucalyptus).

At times, Kenya pays up to Sh21,000 to buy and import a single electricity pole from South Africa. Eucalyptus trees have so far been identified as the best and cheapest raw material for making such poles. They mature faster than all indigenous trees, they grow uniformly and straight, and they are hardwood. So far, Kenya has adopted the cloning technology of the tree genus, and generates the seedlings through the populous tissue culture technology.

Mr Esipisu writes on the environment for the ‘Horizons’ pullout.